1. Technical Field
The present invention relates to a liquid ejecting head ejecting a liquid from a nozzle opening, a liquid ejecting apparatus, and a piezoelectric element having a first electrode, a piezoelectric layer, and a second electrode.
2. Related Art
A piezoelectric element used for a liquid ejecting head or the like is an element including two electrodes and a dielectric film provided therebetween, the dielectric film including a piezoelectric material that has an electromechanical transducing function, and the dielectric film is formed, for example, of a crystallized piezoelectric ceramic.
The piezoelectric element as described above is formed by the steps of forming a lower electrode film on one surface of a substrate (flow path forming substrate) by a sputtering method, forming a piezoelectric layer on the lower electrode film by a sol-gel method, a metal-organic decomposition (MOD) method, or the like, forming an upper electrode film on the piezoelectric layer by a sputtering method, and then patterning the piezoelectric layer and the upper electrode film.
In addition, as the lower electrode film of the piezoelectric element, a film including a diffusion-preventing layer composed of iridium oxide has been proposed (for example, see JP-A-2007-173604).
The diffusion-preventing layer composed of iridium oxide may be formed by sputtering of iridium, followed by thermal oxidation; however, when iridium is oxidized, since its volume is expanded by approximately 2.3 times, after the piezoelectric layer is crystallized by firing, the diffusion-preventing layer imparts a large stress to the piezoelectric layer. As a result, the durability of the piezoelectric layer is degraded, and breakage thereof may disadvantageously occur.
In addition, although an iridium oxide film may be directly formed by sputtering, it is difficult to stably and continuously perform sputtering of an oxide. As a result, an oxide having desired thickness, density, and the like cannot be obtained, and the cost is also unfavorably increased.
In addition, the problems described above are not limited to a piezoelectric element used for an ink jet recording head, and piezoelectric elements used for liquid ejecting heads ejecting other types of liquids and piezoelectric elements used for devices other than liquid ejecting heads also have the above problems.